The New York Times | Anthrax Scare Is Attributed to a Testing Error: "WASHINGTON, March 15 - Health officials believe that a mix-up of samples in a Defense Department contractor's laboratory was behind an anthrax scare Monday and Tuesday that rattled the stock market, set the White House on alert, shut three post offices in the Washington area and led to more than 800 people being offered antibiotics.

A senior military official said in a conference call with reporters Tuesday night that 'quality control problems' at the contractor's laboratory appeared to have caused the bioterrorism false alarm."

(Via NY Times.)